According to the NOAA description, it "rises rapidly in frequency over about one minute and was of sufficient amplitude to be heard on multiple sensors, at a range of over 5,000 km." NOAA's system ruled out its origin as any known man-made sound, such as a submarine or bomb, or familiar geological sounds such as volcanoes or earthquakes. While the audio profile of the bloop does resemble that of a living creature, the system identified it as unknown because it was far too loud for that to have been the case: it was several times louder than the loudest known biological sound. Five other significant unexplained sounds have been named by NOAA: Julia, Train, Slowdown, Whistle, and Upsweep.

Dr. Christopher Fox of the NOAA speculated that the Bloop may be ice calving in Antarctica. A year later Dr. Fox was paraphrased speculating it was likely animal in origin.